Process for producing diazabicyclooctane derivative

A process for producing a compound represented by a Formula (III), comprising:

• reacting a compound represented by the following Formula (I):
• with a compound selected from the group consisting of 1-hydroxypyrrolidine-2,5-dione, 2-hydroxy-3a,4,7,7a-tetrahydro-1H-isoindol-1,3(2H)-dione, 2-hydroxyhexahydro-1H-isoindol-1,3(2H)-dione and 4-hydroxy-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione, allowing a carbonylating agent selected from the group consisting of phosgene, diphosgene and triphosgene to act on the resultant compound to obtain a compound represented by the following Formula (II):
• removing the protecting group P and treating the resultant compound with a base to produce a compound represented by the following Formula (III):
• wherein in said Formulas (I), (II) and (III), OBn is benzyloxy;
• P is an NH protecting group capable of being removed with an acid;
• R1 is 2,5-dioxopyrrolidin-1-yl, 1,3-dioxo-3a,4,7,7a-tetrahydro-1H-isoindol-2(3H)-yl, 1,3-dioxohexahydro-1H-isoindol-2(3H)-yl or 3,5-dioxo-4-azatricyclo[5.2.1.02,6]dec-8-en-4-yl and R2 is hydrogen, ClCO— or Cl3COCO—.